The technology required to build a multiplayer video game supporting a few players on a high-speed local-area-network (LAN) is far different from doing the same thing with many players on a wide area network (WAN) with relatively low speed terminal connections and unknown latency. Adding more realism to the experience requires even more technology advances.
Multi-player games can create considerable bandwidth requirements. Even with all the content stored locally, e.g., in all client machines, state changes in the shared environment come quick and require lots of message traffic. LAN based games typically use "broadcast mode" to send messages to all stations on the network. In wide area networks, when one client station changes the environment, a message must be sent to each of the other players. The number of messages that network must handle goes up by the square of the number of the players. In fast changing environments such as video games, changes in state can come as often as ten times per second.